Here's my humble contribution to the forum. Direct english translation from the article. Do let me know if you succeed with the SILENT mode update. Thanks.
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[Action] [While pressing button] [LCD]
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1 Turn aperture dial to F22 Aperture button
2 Turn camera on SELECT +/-0.0
3 Press SELECT SELECT [0]
4 Turn camera off then on Do not press any buttons [0]
Enter ROM
5 Exp. comp. button [0]
Press right button 1 time r1
Press left button 2 times l2
Press right button 3 times r3
Press left button 4 times l4
Press right button 3 times r3
Press left button 2 times l2
Press right button 1 time r1
6 Turn from f22 to f13 Aperture dial A[83]
Set as A00 Exp. comp. button A[00]
7 Turn dial to f16 D[FB]
8 Set display to D[FA] Exp. comp. button D[FA]
9 Power off f16
10 Press shutter btn for 2 secs Shutter button f16 disappears
Use
11 Press MF when turning camera on L[0]